Hydrologic · Under-Sink RO Systems
Hydro-Logic Stealth RO 300
Lower concern, RO filters typically avoid PFAS-prone materials, but brand transparency is absent.
The Hydro-Logic Stealth RO 300 uses standard reverse-osmosis membrane and activated carbon, both materials not typically treated with PFAS. No public disclosure from the brand about PFAS presence or absence, and no third-party certification.
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RO membrane, carbon filter, stainless steel housing
Brand disclosure
Brand is silent on PFAS
Lab data
No public lab test
Why this grade
No PFAS disclosure
No public statement about PFAS in this product.
Uncoated safe material
Bare, uncoated material (cast iron, stainless, carbon steel, or glass) with no surface treatment to contain PFAS.
The full breakdown
What it's made of and why it matters
The Stealth RO 300 uses a thin-film composite RO membrane (standard across the category), activated carbon pre-filters, and stainless steel housing. The membrane itself does not leach chemicals into water under normal pressure conditions; carbon filters are inert once saturated. Stainless steel (typically 304 or 316 grade in this price tier) is stable and does not corrode into drinking water at neutral pH, though some systems include plastic valves and fittings downstream that warrant attention.
The brand's record and disclosure
Hydrologic does not publish detailed material certifications, third-party test reports, or PFAS-avoidance statements on their website or product packaging. The company holds no visible NSF certification or independent verification of claims. No major recalls or contamination incidents are on public record for this model. Transparency is below industry best practice; competitors like Pentair and GE Water publish material specs and certifications more openly.
How it compares in its category
Under-sink RO systems are among the safest water-treatment appliances because the RO membrane physically removes contaminants rather than relying on chemical coatings or additives. The Stealth RO 300 is mid-range; premium models (Pentair Aqua Systems, GE RO) offer NSF certification and published component specs, while budget models sometimes use lower-grade plastics prone to BPA leaching. This product sits in the middle on transparency and material quality.
If you buy it
Replace the pre-filter (carbon and sediment) every 6-12 months depending on water quality; replace the RO membrane every 2-3 years or sooner if output pressure drops. Flush the system for 5 minutes after installation and monthly thereafter to prevent bacterial biofilm in the membrane. Check rubber seals and plastic fittings annually for cracks; discard the unit if you detect plastic off-odors in the water. Do not heat treated water above 45°C (113°F) to avoid membrane degradation.
Beyond PFAS: other things we checked
Established hazard classes for this product type, assessed from public information. These never change the PFAS grade; a Likely flag caps the Verdict at “Buy with care.”
Bacterial growth in membrane housing or storage tank
Stagnant water in the RO tank or membrane chamber can harbor bacteria if the system sits unused for extended periods. Monthly flushing and draining of the storage tank reduces this risk significantly.
Plastic valve or tubing leachates (BPA or phthalates)
Hydrologic does not disclose material specs for post-membrane fittings and storage-tank components. Cheaper RO systems sometimes use PVC or other plastics with low-dose BPA; no specific test data is available for this model.
RO membrane or carbon filter degradation releasing microparticles
Failure to replace filters on schedule can allow carbon dust or membrane fragments to pass into drinking water. Properly maintained systems pose negligible risk; this is a maintenance issue, not a manufacturing defect.
Housing corrosion or seal failure
Stainless steel housings are resistant to corrosion; no recalls or widespread seal failures are documented for the Stealth RO 300 model series.
Reduced water output indicating membrane fouling or biofilm
Over time, mineral buildup or bacterial biofilm can clog the membrane without contaminating the water directly, but signifies the system is nearing end-of-life and filters must be replaced.
What we don’t know
This grade is a model-based estimate from public materials, coatings, and brand disclosure at 72% confidence. It is not a lab result.
No independent PFAS lab test is on record for this exact product. A lab test could move the score in either direction.
The brand has not made a specific, verifiable PFAS-free statement, so part of this score reflects that missing disclosure rather than a confirmed material.
Formulations and coatings change between production runs. Always check the current label before buying.
More under-sink ro systems grades
How we score: every product runs through the same public 0–100 rubric based on materials, coatings, brand disclosure, lab findings, and recalls. See the full methodology → Spotted a mistake? Report an error.